It’s opening weekend for various concert series, I wound up with three.Single ticket, free to the first request.Friday, 8 pm BEMF Dutch Renaissance music for voice and strings. First church congregational, Harvard Sq.Saturday 3 pm, Blue Heron Renaissance Choir. 16th century French on a theme of nightingales. First Church congregational.Sunday 3 pm. Boston Baroque, Beethoven’s ninth symphony. Jordan Hall, Boston.